Cartridge loading

A MC cartridge is inherently a current generator and the best way to get the ultimate performance out of it is to treat it as such and feed it into a current amplifier.

By definition a true current amplifier would load a cartridge with a dead short which is about as far away from 47K as you can get.

The current injection phono amp is 47 Labs Phonocube (input impedance is ZERO aka "0" )

The current source power amp is First Watt F2J and probably the one and only current source amp on the market, only 100 units made by First Watt. 

I have both in my system

As I have mentioned many times, the input impedance cannot be zero. If it were, you would have no output at all because the signal would be connected directly to ground.  That condition (zero input impedance) is in effect a mute switch. Most "current driven" phono stages that I have investigated in detail, so far as that is possible, because most manufacturers are secretive, have an input impedance of 4 to 20 ohms, depending upon the product.  I am using one now in conjunction with my Ortofon MC2000 that has an input impedance of 10-20 ohms.  With such a value, and given that the MC2000 has an internal resistance of only 2 ohms, you would think the input is voltage driven, in fact, because the ratio of the two impedances is favorable (about 1:10 ratio).  I don't know how it works (current or voltage), therefore, but it works fantastically well, allowing me for the first time to hear the MC2000 and without an SUT.  I have never owned an SUT.

Dave, I read your post after responding to Chakster.  But I hope there will be more comments on loading and especially on "current drive", over and above the discussions you and I have had privately.  On the question of whether increasing the load on an MC might impede tracing of HF encoded on an LP, I have been wrestling with that, as you know. In my own thinking, I start with the well known phenomenon of "back EMF", as I stated elsewhere on this thread, which is a phenomenon associated with driving an electromagnetic woofer, most notably. For an MC cartridge, the groove undulations put mechanical energy into the cantilever. The coil rides on the cantilever and has its own internal resistance related to the wire gauge and the number of turns of wire.  For an LOMC, the resistance is typically low, almost always less than 50 ohms and most often less than 20 ohms. I am wondering whether spurious motion of the coil in the magnetic gap could excite a force that feeds back on the motion of the cantilever so as to dampen or impede it. Then I wonder whether the load resistor might affect the magnitude of that phenomenon. Since the coil resistance is already quite low relative to external load resistance, maybe the value of the load resistance would not make much difference, and therefore there would be not much effect on the tracking of HF. But maybe the difference between 100 ohms and 47K ohms (extreme differences in other words) is significant in terms of the magnitude of the retarding force.  Or is this pure science fiction?
If this notion has any merit, then there would be a big difference among different types of cartridge (MM, MI, etc) as to the magnitude of the effect, because cartridges that are not LOMC typically have much greater internal resistance.

As I have mentioned many times, the input impedance cannot be zero. If it were, you would have no output at all because the signal would be connected directly to ground.

While it is true that no voltage can develop across 0Ω that doesn’t mean that the current that is generated cannot be amplified and then converted back to voltage. While I agree that in reality 0Ω is an impossibility, I am also not convinced it is a good target to shoot for from anything other than an academic perspective. Like everything else in audio, the truth rarely lies at the extremes and lives in the subtleties of the middle.

As I have mentioned many times, the input impedance cannot be zero.

@lewm So the designer Junji Kimura is lieing everywhere about 0Ω inpedance of his own 47 Labs 4712 Phonocube and slightly cheaper 4718 phonostage too, and every reviewer repeating it ? I just don’t understand why then everywhere the input impedance in his special circuit stated as ZERO if it’s 2-4 Ω ? What’s the goal to tell it’s 0 Ω if it’s higher, will it help to sell more units ?

I don't accuse anyone of lying, except a certain President of the USA on some occasions. But manufacturers are sometimes given to hyperbole in their advertising copy, and too, they are sometimes inclined to treat their potential customers as ignorant, such that they feel the need to exaggerate in order to make their point.  Like Intactaudio said, an "ideal" current-driven phono would in fact present a zero ohm input Z. So I would say maybe Mr Kimura is exaggerating.  I never did any research into the 47 Labs product, but I did read as much as I could find about several others, most of which are far more costly than the 47Labs, and some of which have been given rave reviews (e.g., Aqvox, BMC MCCI, etc), and none of those truly provides zero ohms input impedance, if you read the fine print.  But that doesn't lead me to believe they aren't excellent in SQ.  In fact, I think that when M Fremer reviewed the BMC MMCI, he indicated its input Z is about 4 ohms. The one I'm using I know for sure does not give zero ohms input Z, but the sound I get from the MC2000 is superb, and that is what counts. I've also used it with another LOMC (AT ART7) that has a 12 ohm internal R.  Since my unit's input Z is about 20 ohms, it is operating more like a current drive when I use it with the latter cartridge, and it sounds just as excellent.

Dear @lewm  : """  could excite a force that feeds back on the motion of the cantilever so as to dampen or impede it.   """

Could be but I doubt it that could " impede it ". What you said is not related to the loading resistor that's what atmasphere supports alonfg its effects/? ? ?.
Now a cartridge designer/manufacturer takes in count all the elctrical and mechanical scenarios where the cartridge plays its role and seems to me that everything is really claculated witgh " wide " limits for the different play role scenarios due that the cartridge needs/must will performs good in such different scenarios. I don't rthink that in a good top cartridge design we can find out " surprises ".

In theory and due that a LOMC cartridge has a very low inductance the impedance loading ( resistor ) just can't modified ( electrically. ) the cartridge behavior. Instead in the mechanical scenario/land several and different parameters affects and has effects on the cartridge quality performance levels.The " dull " sound that some one posted when the cartridge is loaded with 100 ohms in reality is not a " dull " sound and what happened is that with that kind of load ( tha's the one I use. ) the SPL goes a little ( tiny ) lower and our ears are extremely sensitive with SPL changes especially at HF  but the information is all there and even cleaner that at 47kohms.
I attested that effect with different phono stages in many audio systems including mine.

As time goes on what atmasphere said has lower and lower and les " credibility " especially with out evidence by his part and taking in count the many first hand experiences we have that showed that things are the other way around.
You or intactaudio and other gentlemans as me are not true rookies in analog audio, we know for sure many audio main and critical subjects and if some one or something is out of the normal behavior/experiences then I want to learn two things: first if I'm wrong with all what I learned about or second to confirm that what I learned is rigth. Tha's all.

So we have to wait for the atmasphere precise and specific answer. We will see.

R.

@lewm 

I don't accuse anyone of lying, except a certain President of the USA on some occasions.

Ohh, same here, but 100%

I never did any research into the 47 Labs product, but I did read as much as I could find about several others, most of which are far more costly than the 47Labs, and some of which have been given rave reviews (e.g., Aqvox, BMC MCCI, etc), and none of those truly provides zero ohms input impedance, if you read the fine print. But that doesn't lead me to believe they aren't excellent in SQ. In fact, I think that when M Fremer reviewed the BMC MMCI, he indicated its input Z is about 4 ohms. 

Maybe Kemura's circuit of the 47 Labs Phonocube is just a different design ? Very expensive unit with that power supply, luckily i bought used sample.  

Saying that a (working) phono stage has zero input impedance is similar to claiming to travel at the speed of light or to live forever. It’s a physical limit that one can only approach but never reach, if one actually wants to hear music come out the other end. 1-2 ohms might be possible. I think one unit I investigated got down to 4 ohms.

By the way, I don't think cost is a factor in achieving the lowest possible phono input impedance, if that is the primary goal ahead of performance. I also see that I earlier already suggested that the BMC MCCI affords a 4-ohm impedance.  I am not certain that is correct, but there is one out there.  MCCI is quite low, though.  Meantime, I am waiting for someone to jump on my hypothesis about the effect of load resistance on the capacity of a cartridge to trace HF.  (This has nothing to do with current drive vs voltage drive.) I'm pretty sure I am off the mark.

Saying that a (working) phono stage has zero input impedance is similar to claiming to travel at the speed of light

but this is exactly what i do when i travel back in time to find some rare cartridges 

but this is exactly what i do when i travel back in time to find some rare cartridges

So that is how you manage to find all these rare beasts at bargain bin prices nobody else can ever duplicate!

All makes sense now.

Need to fire up the trusty way back machine and give it a whirl.

😉😉

Hey Lew.

It appears as if this guy has a good take on what is going on with the 0Ω

http://phonoclone.com/diy-pho4.html

I quickly simmed the circuit and it appears as if the input Z is frequency dependent and around 0.001Ω @ 10hz and increases by a factor of 10 for every decade which puts it at 1Ω @ 10khz and 10Ω @ 100khz.  

how you translate this into an easy to understand input impedance for the masses is not an easy task.  Is 0Ω 100% accurate?  no... but for the majority of the audio band it is close. Just try to explain a frequency dependent variable to a group used to values being ruler flat form 20-20K.

In the end I do not think there is anything disingenuous with the claims but once taken out of the context of being an audio generalization for the masses it does become problematic.
 

dave

@lewm  ;: I re-read your post and your hypotesis is only that and I doubt some one can " jump " here to confirm your hypotesis that can " impede it " .
"""  wonder whether the load resistor might affect the magnitude of that phenomenon. """

I can see that you like to make all more " complicated " when the issue posted by atmasphere was diferent to what you posted and I can't understand why not we can go step by step: why add more " phenomenos " to the main issue. I wonder why?

Anyway, you are free to post what ever you want. 

R.

Raul, I have no idea what you are trying to say.  Please clarify. Thanks.
From the one sentence I think I do understand, how can one subtract the effect of the load resistance when the entire question revolves around the value of the load resistance?  Ralph says that low value load Rs tend to impede the cartridge's ability to trace HF.  My idea, for good or ill, is an attempt to explain how that might be the case, but I am saying that the load resistor, for an LOMC, is in parallel with the coil resistance, which is already usually less than 20 ohms.  So the parallel sum of the value of the coil resistance plus the load resistor will always be less than 20 ohms.  In other words, the load resistor does not make a big difference and maybe therefore should not have much effect on the magnitude of any "back EMF" generated at the coil/magnet interface.  This would lead me to disagree with Ralph, but the whole issue is a bit over my head to begin with, and I seek input from others who know more than I do.  There's another way of looking at it, too.

Dear @lewm  :  I understand what you move to post about and I know you that almost always you try to give and explanation/your explanation and this is fine.

Now, I posted that I know that exist no one that can " jump " with true evidence of that " limit trace ability on HF " and I know because in that older thread where I participated where the kind of gentlemans that have a really high technical knowledge levels and rigth there one of them proved to atmasphere that what he said about was and is: false and atmasphere just left with out answer or evidence on the issue, as a fact he stay " dead silence ".

Just like here when I asked to him a precise question to rpove what he is spreading any where for many years and he do that even that was proved to him that is: false.

I that thread no other persons " jump " to shows evidence to confirm that that assumption was not false.

My technical level is very low and that's why I still ask to him for evidence on that " limit trace.."  that like intactaudio I know just does not happens.

I know that you agree that can't happens and that's why you are looking for that " jumping person "  that you posted.

Of course that like you I will love that that person appearead here to tell us that we are wrong and that that " limit trace..." exist and he shows the evidence.

But due to whom is atmasphere and his cotinuos spreading on that issue and with all respect he has the responsability to show that true/live evidence or accept is a misunderstood from his part. He can do the last mantaining his " dead silence " attitude that is a confirmation of no evidence.

The issue/problem is that " limit trace..." I hope he can come back with the evidence where ( I hope ) we can duplicate in our system and be aware about.

R.

Hey Dave (Intactaudio), .001 ohms is still not zero ohms.  I'm just sayin'...But I'm also impressed.  That unit can do the purest "current gain" of any I know about so far.
And, since Chakster can move at light speed, rules fall apart.

Raul, I share your interest in this subject.  But I also know that Intactaudio is one of the smartest guys in the business, even including the persons you have in mind, and I know that he is still thinking on this subject of the effect of load on the motion of the stylus.  I see it as a very complex question, but maybe that is because I myself am so lacking in understanding.  However, as I understand you, your position is that it doesn't happen, because you can't hear it (and because you have the testimony of some other knowledgeable persons who also deny the phenomenon exists).  Is that a fair summation of your position?

Chak, Is THIS what you have?https://audiocubes.com/products/47-laboratory-4712-phonocube

What I experienced always is that at 100 ohms quality level cartridge performance is always better

If your phono section has RFI sensitivity what you state above will be the case as I’ve maintained also on these threads.


With regards to the load impedance affecting the cartridge, of course this happens. Moving coil cartridges work on the same principle as a loudspeaker; now think about a kid’s walkie-talkie that has the speaker also double as a microphone. In other words, the speaker can be driven by energy or it can make energy, because it is a **transducer**, and with any transducer motion is converted to electrical energy and vice-versa.


You can test this easily enough- remove the grill from your speaker and see how easy it is to move the woofer if nothing is attached to the speaker terminals. Then short out the speaker terminals and see how easy the woofer is to move then! With a cartridge its no different- the more you load it down (lower resistance loading resistor) the more work it will have to do and so the cantilever will be harder to move. Since this is also the idea of ’damping’ we can easily infer that mechanical damping of the cartridge will occur if the load impedance is reduced.


Anyone schooled in the electrical arts will understand this immediately; and thus also that high frequency output of the cartridge will be reduced as the cantilever is made to do more work. If this is not readily apparently please do more study of electrical theory.


Now there is one exception with regards to the input impedance of the phono circuit- the load impedance must be connected to the cartridge in such a way that it causes it to do more *work*. If the cartridge is not doing any work then it will be unaffected. Now refer to the article at this link previously given:
http://phonoclone.com/diy-pho4.html

We can see that the cartridge is actually being loaded by the input of the opamp; which if measured will be found to be quite high (most modern opamps are FET input). The idea is to replace the input resistor with the cartridge itself- so that the virtual ground (present in any opamp circuit) is the output of the cartridge itself. In this circuit the cartridge isn’t doing the sort of work as it would be if the cartridge were presented with an actual 0 ohms impedance!! IOW, zero ohms and *virtual ground* are not exactly the same thing! I refer you to OPAMP theory 101 as to why. As a hint, the closer the gain of the opamp is in open loop to infinity, the more the virtual ground will behave as it it is zero ohms **as far as the opamp is concerned**. This is more of a control theory thing which is far more text than I have time to put here, especially since you’ll need an EE degree to follow along. Just take it for now that a virtual ground isn’t the same thing as actual ground or zero ohms! If it were, no amplification could occur!

@lewm

Is THIS what you have?https://audiocubes.com/products/47-laboratory-4712-phonocube

Yes, it doesn’t work without special power supply, so there must be a power humpty (first in the list) and i have it with my phonocube.

If you’re buyin’ a Phonocube without power supply it looks like a good deal, but it doesn’t work. The power supply is 3 times bigger than the cube itself and superheavy. For superb results some people use 2 power supplies for 1 Phonocube (dual mono).

More images of this set with power supply and cube are all HERE (not mine).

And you can study about parts and its unique but very simple circuit HERE.
Let me know what you think now when that guy cracked it and explained why the input impedance is almost ZERO. But that guy is not the designer of the Phonocube, he just made a clone.

P.S. I think i posted all these in another thread long time ago.
The PhonoCube originally designed for Miyabi 47 Lab cartridge. 

Which current injection phono stage do you use ?

Let me know what you think now when that guy cracked it and explained why the input impedance is almost ZERO

@chakster This statement isn't correct. The **virtual ground** is almost zero, not the actual input impedance. Its a bit tricky explaining what the difference is but put it this way, if you turn the unit off you'll find that the actual input impedance is quite high. Apparently it has a pretty good opamp, since that is required in order for the virtual ground to approach zero.

The idea is to replace the input resistor with the cartridge itself- so that the virtual ground (present in any opamp circuit) is the output of the cartridge itself. In this circuit the cartridge isn’t doing the sort of work as it would be if the cartridge were presented with an actual 0 ohms impedance!!

Very interesting @atmasphere  
I wish i could understand more, they don't make Phonocube any longer, probably because they do not make Miyabi 47 cartridge anymore.  

Any other phono stages with the same circuit ? 

Dear @atmasphere  : Your post is not an answer to what I asked to you:


"""   how did you measure that " limit trace " as a function of loading and which is the point/value where the loading figure starts to " limit trace " abilities in the cartridge?  """

that is what needs a more specific answers because you posted here and in several other ocasions:

  """ will limit the ability of the cartridge to trace higher frequencies .."""


 Lewm my answer to you is that other than " science " we have to use common sense and here what I posted before to you:

"" did you know how much " force " do you need to apply/need/ at the base of the cantilever to really impedes at the stylus tip position its free movements, a tiny movement? no? 
Btw, do you know the " power forces/inertia " generated at the stylus tip when ridding the grooves at 33/45 rpm and what " force " is need it to " limit the trace " of the stylus tip to track when appliyed that force/loading at the other end of the cantilever? ..."""

Which is the force need it to broke that very high inertia generated by the friction between the groove modulations and stylus tip when the cartridge is ridding/tracking those grooves that can " limit trace HF "" ?

I don't know that answer concerning the loading resistor value to broke that inertia. We have to think that load resistance takes its effect at the cantilever base and the stylus tip is ridding at the other end/extreme of the cantilever and this makes " things " extremely complicated to that " limit trace " issue.

That theorical electrical loading effect is converted in mechanical energy ( the " force ". atmasphere said: stiffer the cantilever. ) what makes it even more complex due that in the mechanical land we have to take in count several parameters as: compliance of the cartridge, cantilever length and overall dimension and characteristics, status of the stylus tip because if the cartridge has over 1.5 khours of use its own tracking abilities changed that when the stylus had only 300 hours and not only that but even its compliance through more playing hours could changes too, the stylus tip inertia is different depending its position in the overall LP grooves and other parameter to take in count is the different velocities recorded through the LP grooves surface, etc, etc.

So, till now exist no true evidence that that " limit trace..." can happens.

@atmasphere can you answer the original questions?

R.

Dear atmasphere : You already had all the time and opportunities to show the evidence I asked about on that specific: " limit trace....".

Today I'm totally convinced that you has no evidence about evidence that we can duplicate in a system or at least evidence.

So Palmer was rigth ( years ago. ) when he proved that your " limit trace..." statement is FALSE.

For my part end of the issue due that now I can confirm that  the ones that like me that think that " limit trace.."" does not exist  we all are rigth and that's  what we need to know  thank's to your " answer ".

So never mind about, subject solved.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Your post is not an answer to what I asked to you:

Simply put, I've answered your question directly several times in this thread alone. I've been avoiding saying this, but at this point its apparent that you don't understand the answer;  you respond with literally:

Bla, bla, bla, bla, bla, 

Again, electrical damping of an electro-mechanical transducer results in less high frequency output of that transducer. I suggest you study the topic with the same sort of energy that you've used in your attacks.

Chakster, I am experimenting with a device made by Intact Audio.  It's a prototype, one-off, not in production.  It's "based on a Nelson Pass I/V converter for current output DACs", according to Intact Audio.  It is not a phono stage per se; it is inserted into the chain between the LOMC and the input of an MM phono stage, or any phono with a 47K input resistance (I guess).  The output of the IA device drives the MM input of my Manley Steelhead, set at 50db of gain. (There is no added gain from the high level section of the Steelhead.)  No hiss or otherwise intrusive noise or hum allows me to appreciate the MC2000 for the first time. (I don't own the T2000 SUT or another SUT with similar characteristics.) 

atmasphere : You are so " curios " when posted:

""  electrical damping of an electro-mechanical transducer results in less high frequency output of that transducer.  ""

no one is questioning that ( at least not now. and is not what I asked several times here and in other threads. ).

What I asked you are true evidence of your statement about that: 

""" LIMIT TRACE....."""

wich of your words you don't understand?, that was the issue. Not any more and at least for me is clear that your statement about is totally: FALSE. That's a lie till some one prove that " limit trace .." is not false.

R.

"" electrical damping of an electro-mechanical transducer results in less high frequency output of that transducer. ""

no one is questioning that ( at least not now. and is not what I asked several times here and in other threads. ).

So we are in agreement as seen above. That is the same as:

What I asked you are true evidence of your statement about that:

""" LIMIT TRACE....."""

IOW when the cartridge is loaded (damped) its ability to trace high frequencies is reduced because the cantilever will be stiffer. If you agree with your first post above as you say you do, then you have to agree with this also. They are the same.

atmasphere : """    is loaded (damped) its ability to trace high frequencies is reduced because the cantilever will be stiffer... """

I said " at least not now...".

For the lectrical loading could " limit trace... " it needs that the cartridge be overdamped and the cartridge designers already has all calculated for that kind of cartridge behavior never be present or even approach it. It's almost the same in tonearm designer calculations when they design the use of oil/silicon damping, they make the calculation for overdamping can't happens because overdamping limit the trace of the stylus tip ridding during play the LP.

Now I ask for numbers/value of that loading resistor to " limit trace... "  and you don't show any " numbers " about that can be corroborated.

No one wants an overdamped cartridge: electrically or mechanically, these is out of question.


This is what I posted to lewm in this same page for you can read it:


"" did you know how much " force " do you need to apply/need/ at the base of the cantilever to really impedes at the stylus tip position its free movements, a tiny movement? no?
Btw, do you know the " power forces/inertia " generated at the stylus tip when ridding the grooves at 33/45 rpm and what " force " is need it to " limit the trace " of the stylus tip to track when appliyed that force/loading at the other end of the cantilever? ..."""

Which is the force need it to broke that very high inertia generated by the friction between the groove modulations and stylus tip when the cartridge is ridding/tracking those grooves that can " limit trace HF "" ?

I don't know that answer concerning the loading resistor value to broke that inertia. We have to think that load resistance takes its effect at the cantilever base and the stylus tip is ridding at the other end/extreme of the cantilever and this makes " things " extremely complicated to that " limit trace " issue.  """


Did you read it?  because is all common sense.

So, your " limit trace ..." statement continue be false.

R.

So, your " limit trace ..." statement continue be false.

Your feculent argument is also specious. You can't have it both ways.

rauliruegas

Of course you have nothing about. So what you still post is false and a lie. Period.

I think Ralph has been very patient with you and perhaps part of the problem here has been a language barrier. That's why I'm telling you this: Accusing someone of lying is an insult bigtime, and your accusation may reveal more about you than you intended.

A MC cartridge is inherently a current generator

Why? By the Faraday law of induction, changing in time magnetic flux generates voltage (EMF) across the coil not current. Current flows when you close the circuit with a load.

A MC cartridge is inherently a current generator

I want to be clear that I was not stating this as my belief but to point out it is an argument made for using a current amplifier rather than a voltage amplifier.

My personal take on it is that the coil generates what you tell it to.  Leave it open it generates voltage, Load it down it generates current.

dave

I don't agree. Coil moving in a magnetic field can generate only one thing - voltage. This is the lesson of papa Faraday :)

Of course, until the circuit is closed, there is no current.  The issue of whether a cartridge is high current/low voltage, or vice versa, is only meaningful in the context of what the downstream amplification needs.  In the case of a cartridge, the phonostage requires higher voltage than the cartridge delivers, so in that sense, the cartridge is low voltage/high current.  A step up transformer steps up the voltage delivered into the phonostage by converting current to voltage; an active MC first stage also jacks up the voltage.

Interesting I read early on a list of preamps that were Not up to the task.  I want to mention the one, the XONO.  Michael reviewed this phonostage and said it was one of the best he ever heard.  How much could things have really changed since then....?  Just goes to show you we all hear differently.

I don't agree. Coil moving in a magnetic field can generate only one thing - voltage. This is the lesson of papa Faraday :)

OK  you win :-)  

Ralph... If I can ask you a question which might clear up a lot of things here....

IOW when the cartridge is loaded (damped) its ability to trace high frequencies is reduced because the cantilever will be stiffer.

when you say "ability to trace" are you referring to the output generated by the cartridge or the physical ability for the stylus to remain in contact with the groove wall?

dave

bydlo and larry, I wouldn't argue with what you both say, but I would point out that the capacity of a LOMC to make signal current into a very low resistance load (meaning a load that is equal to or much lower than its internal impedance) does not usually parallel its capacity to make voltage into a "high" resistance load (meaning any load that is about 10X the coil resistance). (I am not getting into the argument between Raul and Atma-sphere.)  For example, my MC2000 is rated for 0.05mV at the standard stylus velocity.  But its internal resistance is only 2 ohms. Thus it can generate 25uA of current into no load or probably anything much lower than 2 ohms.  For comparison, my Audio Technica ART7 has twice the voltage output of  the MC2000 (0.12mV) but also has an internal impedance of 12 ohms at 1kHz.  Thus the ART7 is less efficient at generating current (10uA), when forced to do so, than the MC2000.  Viewed this way, the MC2000 more than holds its own for current output, among very LOMC cartridges. So, I think the point of a "current-driven" phono stage is that it might be advantageous compared to stages that are voltage driven, only for certain very LOMC cartridges.  It certainly has been demonstrated in my system with the device made by Intact Audio. No one views the idea of current-drive for phono as a panacea for all LOMC cartridges, but the flexibility is there.

Dear @cleeds  : "  I think Ralph has been very patient with you...""

Patience?, I have years wating for his numbers about and he only showed and shows : empty words even that Palmer proved that that " limit trace.." is false and he posted that way: false.

In the other side I was not who posted the " limit trace..." issue but he was and that's why I asked about.

Now and in good shape: which the word to name some one that spreads for years and continue spreading false information?

Btw, I think he choose the wrong words: " limit trace... " to explain his way of thinking. 
I don't care about any more because we are talking of false information.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

My personal take on it is that the coil generates what you tell it to. Leave it open it generates voltage, Load it down it generates current.

@intactaudio 

To be clear, a current amplifier does not significantly load the cartridge. The 'zero ohms' thing that you see talked about in reference to them refers to the virtual ground with which the cartridge plays a part. Virtual ground being nearly zero ohms is **in no way** similar to actual ground!! So the cartridge does not behave as it its driving a short. It behaves as if it is driving a fairly high impedance. This may sound counterintuitive, but a virtual ground is a thing that has to do with how OpAmps work and if it was really the same thing as zero ohms, the OpAmp wouldn't work. Another way of putting this is that 'virtual ground' is a charged term in that it does not mean 'ground' at all. The word 'virtual' means something different than 'actual' :)

when you say "ability to trace" are you referring to the output generated by the cartridge or the physical ability for the stylus to remain in contact with the groove wall?

I am referring to the simple fact that a stiffer cantilever will be unable to trace higher frequencies- at some point, it won't be able to follow the groove wall impressed with higher frequencies. This point may be outside of the audio band, but the way some people try to use loading resistors as a tone control, with some cartridges I suspect it will be inside the audio band too. Regardless, by loading the cartridge in a significant manner, causing the cantilever to be less supple is unavoidable.


The reason I do not think cartridge designers design for any load other than 47K is twofold: first, 47K is the industry input impedance standard for phono preamps. Second, I had a conversation with Jonathan Carr (well known of Lyra fame) on this very topic and it was he who mentioned to me that loading at 100 ohms or the like would have the effect of reducing high frequency performance (this conversation occurred in my room at the 2014 Munich show; we had both been active on a thread on cartridge loading that can be found on the 'What's Best' audio forum). This issue was at the heart of the conversation- it was not about anything else. Now as a phono preamp designer, having this conversation with a top cartridge designer, and understanding basic physics of how transducers work, this confirmed my own work in the area. He and I are on the same page with anything to do with cartridge loading, not just the cantilever stiffness issue.

If you know how electro-mechanical transducers work, you can't come to any other conclusion. To make things easier to work with, we humans often simplify a picture so we can deal with basic concepts. Making the cartridge output invariant as if it somehow does not obey Ohm's Law and basic generator theory (see https://en.wikipedia.org/wiki/Generator_(circuit_theory)) is one of those ways of simplifying a concept.  But if you understand that a cartridge is a generator, maybe this idea is easier to understand in that a conventional generator which is spun to make electricity, the generator shaft becomes progressively harder to spin the more the generator is loaded. A cartridge **has** to have a similar behavior!

rauliruegas

Dear @cleeds : " I think Ralph has been very patient with you...""

Patience?, I have years wating for his numbers about and he only showed and shows : empty words

We are off-topic. Briefly, no matter how impatient or unhappy you are, your accusations against Ralph - in particular, that he has lied in the forum - are unwarranted. The two of you seem to disagree, which is not unusual here. Yet you continue to prosecute your case with insult.

As I mentioned before, I think some of the problem here may be a language barrier. Please consider that.

atmasphere

... if you understand that a cartridge is a generator, maybe this idea is easier to understand in that a conventional generator which is spun to make electricity, the generator shaft becomes progressively harder to spin the more the generator is loaded. A cartridge **has** to have a similar behavior!

That's a great analogy! Thanks for sharing, Ralph!

bydlo and larry, I wouldn't argue with what you both say, but I would point out that the capacity of a LOMC to make signal current into a very low resistance load (meaning a load that is equal to or much lower than its internal impedance) does not usually parallel its capacity to make voltage into a "high" resistance load (meaning any load that is about 10X the coil resistance). (I am not getting into the argument between Raul and Atma-sphere.) For example, my MC2000 is rated for 0.05mV at the standard stylus velocity. But its internal resistance is only 2 ohms. Thus it can generate 25uA of current into no load or probably anything much lower than 2 ohms. For comparison, my Audio Technica ART7 has twice the voltage output of the MC2000 (0.12mV) but also has an internal impedance of 12 ohms at 1kHz. Thus the ART7 is less efficient at generating current (10uA), when forced to do so, than the MC2000. Viewed this way, the MC2000 more than holds its own for current output, among very LOMC cartridges.

@lewm What you are describing is the fact that the lower output resistance of a voltage generator, the more current efficient it is. This does not change the fact that by the laws of induction MC and MM carts are both voltage generators.

I wouldn't worry about whether a cartridge is a voltage or current generator- the simple fact is current does not exist without voltage and vice versa. I think this might have come up on account of current amplifier phono sections, which have that low 'virtual ground' thing going on.


Just because its a current amp does not mean you need the source to make only current.

At any rate, a cartridge makes **power** since its a generator; there is voltage and current at the same time.

I was merely pointing out that there is some merit in this idea of a "current-driven" phono stage for certain very LOMC cartridges, even though the use of the term may be semantical or to put it another way, an exaggeration.  On a practical level, I hear it.  I was maintaining a priori in my discussions with Chakster that the input impedance of most such phono stages, or phono stages that have been marketed as "current-driven" is not zero.  So I don't disagree with any of the above. The key word is "marketing". Anyway, I am quite pleased with the result.

Ralph,

To be clear, a current amplifier does not significantly load the cartridge. The 'zero ohms' thing that you see talked about in reference to them refers to the virtual ground with which the cartridge plays a part.

I built a spice simulation of the circuit in question and while the input Z was not 0Ω, it was low and followed the  output V / R pattern that Lewm described.  When I placed a 0.05mv 2Ω source it delivered 25µA of current into the phonoclone circuit.

I am referring to the simple fact that a stiffer cantilever will be unable to trace higher frequencies- at some point, it won't be able to follow the groove wall impressed with higher frequencies.

I believe that if a cantilever is either too stiff or too compliant it will have issues tracking high frequencies.   As for 47K being the optimal load,  I see all kinds of manufacturers suggesting values other than 47K as the optimal load for their cartridges.  

dave

 As for 47K being the optimal load, I see all kinds of manufacturers suggesting values other than 47K as the optimal load for their cartridges.  

47K is the industry standard; as far as what it the optimal load that is what this thread is about :)

47K only work under a limited range of circumstances - mostly whether or not the phono section is stable enough to deal with the ensuing RFI to which it will be presented when dealing with that impedance. A secondary issue is whether or not the cartridge was built with some form of electrical damping in mind with the intent of thus creating mechanical damping. This seems problematic as the compliance of the cartridge is directly affected- that being the case a range of loading values would be specified for a given effective mass and we certainly are not seeing that in the spec sheets!

Dear @intactaudio  : atmasphere posted to you:

"""   first, 47K is the industry input impedance standard for phono preamps. Second, I had a conversation with Jonathan Carr (well known of Lyra fame) on this very topic and it was he who mentioned to me that loading at 100 ohms or the like would have the effect of reducing high frequency performance....""

btqw, the 47k industry standard has no direct relationship with LOMC because 47k was choosed for the MM cartridges before the existence of MC cartridges and even that latter on appeared the MC 47k stays for the owners can use SUTs because does not existed active high gain phono stages.


Now, atmasphere said: " i had a conversation... "" . He talked with no evidence of that conversation that showed that " limit trace  " in anyway.
Atmasphere mentioned WBF where JC participated and in that forum JC never mentioned that " limit trace... "  that ( for me ) exist only in the atmasphere imagination and as Palmer said is false..

Here are the main JC highligths when he posted down there in the loading subject:



"""     Regarding loading of low-impedance MC cartridges, in general I recommend trying to reduce any capacitances present between cartridge and phono stage input to as little as possible. Use the lowest-capacitance phono cable that seems decent, turn off any additional capacitance in the input stage of the phono amplifier etc.

The reduced capacitance should make it possible for you use a wider range of loading impedances without having the sound go bright, peaky or thin-bodied. Conversely, any excess capacitance between cartridge and phono stage input will almost certainly force you into choosing lower loading impedances to save your ears.

Being able to use higher-value loading impedances should allow you to hear more of the dynamics and resolution that the cartridge is capable of, while using lower-value loading impedances will limit how much of the cartridge's dynamics and resolution that you can usefully extract.

As you said, live music is energy, and audio reproduction equipment should suppress that energy to the least extent possible.

hth, jonathan  """


normally cables does not comes with low capacitance ( 32pf as the JC cables. ) but a little high one.




"""  My comments are based on an objective understanding (measurements, calculations, and simulations) of what a low-impedance cartridge generator is, what an interconnect is, what happens when the two are combined, what happens when resistors of various values are added to the mix, and what happens when extra capacitance is added. A low-impedance cartridge has an inductive generator, while a phono cable has significant capacitance. Put the two together and you get a huge spike at ultrasonic frequencies. These frequencies are much too high for any human to hear directly, but fall in a band that is likely to impair the linearity of the phono stage in much the same manner as excessive RF. When we "load down the cartridge", for the most part we don't affect what the cartridge does at all (unless the value of the load approaches or drops below the internal impedance of the cartridge). What adding resistive loading at the phono stage input accomplishes is to dampen the resonant energy of the ultrasonic spike, and give the phono stage an operating environment isn't so likely to trigger any latent non-linearity tendencies that the phono stage circuitry may have.

For the reasons given, the phrase "cartridge load" is misleading. "Phono stage input terminator" is a better description of what really happens.

Increased capacitance between cartridge and phono amplification circuitry will lower the frequency of the ultrasonic spike, which requires the application of lower resistive values to dampen the spike. Reduced capacitance between cartridge and phono amplification circuitry will increase the frequency of the ultrasonic spike, which can be tamed with higher-value resistive values.   """




some one there tell JC the first statement here and followed by JC answer:


""" 
you are not really affecting the audible high frequencies with any resistive load shown.

JC: 
Not directly, no. To claim that the loading affects the measurable frequency response of the cartridge is bogus. However, if inappropriate loading bathes the phono stage in copius amounts of high-frequency noise, it may start to distort (unless the designer implemented various techniques to make sure that this won't happen), and the result will likely be intermodulation distortion. IMD products can go low enough to fall within the audible band (even when the stimuli are ultrasonic), and IMD nearly always is not harmonically related to the signal, making it particularly grating to the ear.   ""


JC followed wiith this on his cartridges:



""" When authoring the documentation for our post-2009 cartridges, I went up as high as 600pF cable capacitance (to cover audiophiles who may keep their turntable in a separate room / closet). The official loading recommendations for the Delos, Kleos, Atlas, and Etna reflect this wide range of cable capacitances, and the inclusion of highly capacitive cables for special circumstances is why you may see loading values as low as 95 ohms suggested in our literature. """


"""  jc
Higher capacitance values should be paired with lower resistance values, and vice versa.

The loading resistor value is placed across the phono cartridge's output terminals, which means that any output voltage produced by the cartridge will be forced to flow through the load resistor in the form of current. The higher the load resistor value is, and the farther the net impedance is from the cartridge's internal resistance, the less current will be produced. Conversely, the lower the load resistor value is, and the closer the net impedance is to the cartridge's internal resistance, the more current will be produced.  """


This is what a pair of audiophiles posted there:


"""  I have been experimenting lately with resistive loading on my Pass XP-27 phono stage. I am using the stock SME phono cable that came with my 30/12A table. I have an AirTight Supreme cartridge. I am finding that my previous setting of 47K ohms now sounds a bit flat and thin to me. There seems to be a lot of resolution and dynamics but the sound is a bit less natural or real than I am finding with lower settings. I have been gradually lowering the load values (increasing the load) and am now comparing the 500, 350, and 220 ohm settings. I prefer these because they seem to improve the sense of weight, body, tonal richness and warmth of real instruments without seeming to diminish dynamics, liveliness or resolution. In fact, the resolution seems greater. There is also an increased sense of palpable presence and more natural sound.
 Nick (Doshi) also pointed out that the added "detail" at the say higher loadings actually obscures "real" information. I hear what he’s talking about with the Atlas and other cartridges


My MSL Platinum signature was best with 250ohm at the time with Magico M3 and pass xp-25. Now with Pass xs i prefer 330ohm.
1k and higher it becomes thin and i hear distortions.

So i think your recent findings are right. """



 @intactaudio  and friends we can read in those posts that JC never mentioned " limit trace... ".

JC is very knowledge gentleman not only in cartridges that's his speciality but he knows a lot on tonearms, TTs and Phono Stages because he contributed in a very well regarded PS design and build it.
I know him very weel and I know that what he post he posted because he has evidence because he always makes calculations, charts, modeling and the like. He is not a stupid person, is some one I respect a lot even that in the past he and me do not been in agreement in some issues mainly because my amateur knowledge levels.


Btw, here what Ortofon said on the loading issue and that's different to what JC posted:

"""  The lower the load impedance, the higher the current and the more dynamic the sound.

Best regards
XXXXXX
Ortofon A/S

[FONT=&amp]Playing with the input impedance means also playing with the sound character. The influence of the load impedance on the differences in sound is caused by the change of the crosstalk levels and the amplitude raise at the resonance frequency. The lower the load impedance, the higher the current and the more dynamic the sound.[/FONT]  """



So and for me, the " limit trace..."  issue is still false till some one can comes here ( as @lewm said: jumps here. ) and proves/shows true evidence and not bla, bla.


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

A secondary issue is whether or not the cartridge was built with some form of electrical damping in mind with the intent of thus creating mechanical damping. This seems problematic as the compliance of the cartridge is directly affected- that being the case a range of loading values would be specified for a given effective mass and we certainly are not seeing that in the spec sheets!

@atmasphere  I'd imagine the compliance change may not be big in the manufacturer specified load range so no one cares. Plus  load optimization is usually done by ear anyway.